Multielement analysis of biological reference materials by total-reflection X-ray fluorescence and inductively coupled plasma mass spectrometry in the semiquant mode

Summary Total-reflection X-ray fluorescence (TXRF) and inductively coupled plasma mass spectrometry (ICP-MS) were used for the analysis of two biological reference materials. The quantifications were carried out after addition of one single standard element which serves as an internal standard in both cases. The results of TXRF analysis were good to satisfactory. The method is therefore suitable for fast multielement analysis, because it needs no special calibration specimens. The results of ICP-MS analysis are at least in the order of magnitude of the certified values. In some cases recoveries fit very well. For quantitative analysis, however, the use of the standard addition method or the calibration with external standards is required.     

Study of metal containing hydrogenated carbon films by STM/AFM and SAXS

Metal-containing amorphous hydrogenated carbon films are of high interest for industrial applications because of their excellent frictional properties, their high abrasive wear resistance and their electrical conductivity, which can be adjusted in a range of 10–12 orders of magnitude. In order to get insight into the mechanical and electrical properties it is necessary to study the nanostructure of the films. The structure consists of small nanometer sized metallic or carbidic particles, which are embedded in a three dimensional amorphous hydrogen-carbon matrix. Anomalous small angle X-ray scattering (ASAXS) and scanning tunneling microscopy (STM) have been used to determine size- and distance-distributions of the particles as a function of metal content. Problems and restrictions of both methods will be discussed. Furthermore the capabilities of scanning probe techniques to distinguish different materials on a nanometer scale (material contrast) have been studied employing barrier height imaging (dI/dz) and friction force microscopy.Dedicated to Professor Dr. rer. nat. Dr. h. c. Hubertus Nickel on the occasion of his 65th birthday     

Mass spectrometric analysis of ceramics after decomposition with elemental fluorine

The features of a combustion with elementary fluorine for the case of compact SiC ceramics and model substances for boron containing ceramics (H₃BO₃ and Na₂B₄O₇) were investigated with the aim of their decomposition and analysis. On-line detection of the gaseous decomposition products by quadrupole mass spectrometry using electron impact ionisation was studied. Limitations by blanks and transport interferences were investigated. Standard addition as well as the isotope dilution technique were used for calibration in the case of B, C and W at the trace and major component level.Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthdayDeceased May 1995.     

Circular Dichroism of Some 2-(Phenylmethyl)pyridine Derivatives

The absolute configuration of the 2-(phenylmethyl)pyridine derivatives 1 – 9 had been established by X-ray diffraction and chemical correlation. Their CD spectra have been studied in different solvents for the free and protonated forms. It has now been found that, from the sign of the strong CD couplet between 270 and 220 nm, which was observable for all these compounds besides 7 and 9 , their absolute configuration can be determined much quicker.     

DSC measurements on full thickness mice skin

Highly lipophilic basic drugs, the antiestrogens AE1 and AE2 shall be delivered transdermally. DSC as an additional tool in combination with classic investigation techniques should be used to clarify permeation enhancement. Skin treatment with pure solvents, polyethyleneglycol (PG) and dimethylisosorbide (DMI), slightly changed the phase transition temperatures. Formulations containing lauric acid markedly shifted these transitions to lower temperatures, indicating a lipid-fluidising action of lauric acid. In those cases an additional endothermic peak was observed around 40°C, which is attributed to the melting of crystalline lauric acid. Since the DSC program started at -20°C, it is very likely that lauric acid in the skin samples crystallized. A formulation of polyethyleneglycol and lauric acid leads to significantly higher deposition of lauric acid into the skin, in opposition to dimethylisosorbide/lauric acid formulation. These findings correspond to the results from our in-vitro permeation studies, where a significantly higher transdermal steady-state flux of lauric acid from polyethyleneglycol-formulation in comparison to dimethylisosorbide-formulation was observed. By this unique combination of polyethyleneglycol and lauric acid, the barrier is obviously modified in a way, which allows the highly lipophilic antiestrogens to permeate easily through the skin. So, from this formulation steady-state fluxes of AE-1 were observed, representing approximately the same value compared to the unhindered permeation through skin without stratum corneum. The grade of temperature shift on the skin lipids to lower temperatures can be correlated with softening effects and the enhancement potential of the formulation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Ion chromatographic determination of platinum in biotic materials

A method for the determination of platinum is presented. The procedure consists of a high-pressure digestion of the sample followed by an ion Chromatographic separation. Then the platinum chloro complex is detected by UV-absorption.